1. Field of Invention
The present invention relates to a small generator utilizing a hydroelectric generated by a water flow passing through a faucet and a Water tap apparatus contains a small generator is provided.
2. Related Art
Conventionally, there is widely provided an automatic Water Tap apparatus contains a sensor sensing that a hand held out beneath a faucet. Then the faucet starts to flow water from is on the basis of the sensor sensing. In recent years, moreover, there is proposed an apparatus such that a small generator is provided in a fluid path of such an automatic Water Tap apparatus and a power generated by the small generator is storaged to complement for the power consumption of a circuit such as the sensor as shown in Japanese Utility Model Publication Hei. 2-65775.
The structure of the small generator will be briefly described below. A hydraulic turbine is provided in a fluid path to be a water flowing path and rotates by receiving the hydroelectric of flowing water. A rotor is fixed integrally with the rotary shaft of the hydraulic turbine. The outer peripheral surface of the rotor is a magnetized as a rotor magnet. The rotor magnet is opposed to a stator pole through the wall of a non-magnetic member. Moreover, single layer stator coil is provided to be interlinked with a magnetic flux passing through the stator pole. Then, the hydraulic turbine rotates by receiving the hydroelectric of the flowing water so that a magnet rotates relatively with respect to the stator pole. Therefore, the flow of the magnetic flux flowing to the rotor and the stator pole is changed. As a result, a current flows to the stator coil in such a direction as to prevent the change in the flow of the magnetic flux. After the current is rectified, it is stored in a storage battery.
As described above, the magnetic flux flows between the rotor and the stator pole in the generator. The magnetic flux acts as a resistance when the hydraulic turbine is to be rotated by the hydroelectric caused by flowing the water. In other words, a magnetic flux generated between the rotor and the stator pole acts as a detent torque to brake the operation of the hydraulic turbine during the starting and rotation of the hydraulic turbine. Accordingly, in order to rotate the hydraulic turbine, it should receive a flow amount and a hydraulic pressure beyond a predetermined value. Therefore, if the flow amount is small or the hydraulic pressure of the flowing water received by the hydraulic turbine is low, the hydraulic turbine is neither rotated nor generates a power. If the magnetic force of the rotor magnet is low, the detent torque is reduced so that the hydraulic turbine itself is rotated Consequently, an induced voltage generated during the rotation of the rotor is also dropped so that the amount of power generation is extremely increased. In order to obtain a desirable amount of power generation, it is necessary to increase the magnetic force of the rotor magnetic to some extent and to maintain the flow and hydraulic pressure of a fluid for rotating the hydraulic turbine to some extent.
Under such circumstances, in the small generator for the automatic Water Tap apparatus which has been used widely, if the flow is specifically set to 3 liters/minute or less, the detent torque acts as a resistance so that the hydraulic turbine cannot be smoothly rotated. In order to rotate the hydraulic turbine, it is necessary to set the flow more than 3 liters/minute.
Water saving has been demanded for a long time in respect of the improvement of the environment and other various problems. Under such circumstances, there has been a problem in that the amount of water to flow at a time should be reduced as much as possible also in the automatic Water Tap apparatus. In addition, in the present situations in which a user's critical mind for water saving has been enhanced, the hydraulic pressure of the water discharged with the flow should also be reduced. It is necessary to give such an image that the water saving is being carried out through a drop in the hydraulic pressure.